Identification of Contamination in a Lake Sediment Core Using Hg and Pb Isotopic Compositions, Lake Ballinger, Washington, USA

Abstract

Concentrations and isotopic compositions of Hg and Pb were measured in a sediment core collected from Lake Ballinger, near Seattle, Washington, USA. Lake Ballinger has been affected by input of metal contaminants emitted from the Tacoma smelter, which operated from 1887 to 1986 and was located about 53 km south of the lake. Concentrations and loadings of Hg and Pb in Lake Ballinger increased by as much as three orders of magnitude during the period of smelting as compared to the pre-smelting period. Concentrations and loadings of Hg and Pb then decreased by about 55% and 75%, respectively, after smelting ended. Isotopic compositions of Hg changed considerably during the period of smelting (δ202Hg = -2.29‰ to -0.38‰, mean -1.23‰, n = 9) compared to the pre-smelting period (δ202Hg = -2.91‰ to -2.50‰, mean -2.75‰, n = 4). Variations were also observed in 206Pb/207Pb and 208Pb/207Pb isotopic compositions during these periods. Data for Δ199Hg and Δ201Hg indicate mass independent fractionation (MIF) of Hg isotopes in Lake Ballinger sediment during the smelting and post-smelting period and suggest MIF in the ore smelted, during the smelting process, or chemical modification at some point in the past. Negative values for Δ199Hg and Δ201Hg for the pre-smelting period are similar to those previously reported for soil, peat, and lichen, likely suggesting some component of atmospheric Hg. Variations in the concentrations and isotopic compositions of Hg and Pb were useful in tracing contaminant sources and the understanding of the depositional history of sedimentation in Lake Ballinger.

Department(s)

Geosciences and Geological and Petroleum Engineering

Keywords and Phrases

Contaminant sources; Isotopic composition; Lake sediments; Mass-independent fractionation; Metal contaminants; Negative values; Seattle; Washington; Sediment core; Smelting process; Three orders of magnitude; Washington; USA; Chemical modification; Impurities; Isotopes; Lakes; Lead; Lead smelting; Mercury (metal); Pollution; Sedimentology; Sediments; Lake pollution; atmospheric deposition; concentration (composition); depositional environment; lacustrine deposit; lead isotope; lichen; mercury (element); peat; pollutant source; sediment pollution; sedimentation; smelting; Lake Ballinger; Seattle; United States; Washington [United States]

International Standard Serial Number (ISSN)

0883-2927

Document Type

Article - Journal

Document Version

Citation

File Type

text

Language(s)

English

Rights

© 2013 Elsevier, All rights reserved.

Publication Date

01 Feb 2013

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